Field of the Invention
The present invention relates to an imprint method, an imprint apparatus, and an article manufacturing method.
Description of the Related Art
An imprint apparatus is coming into practical use as a lithography technique for mass production of magnetic storage media and semiconductor devices. An imprint technique is a method of forming a pattern on a substrate such as a silicon wafer or a glass plate by bringing a mold on which a fine circuit pattern has been formed and a resin applied onto the substrate into contact with each other.
For example, in forming the circuit patterns of the semiconductor devices, an overlay (alignment) accuracy between the circuit pattern which has already been formed on the substrate and the circuit pattern which is to be formed from now on is very important. The imprint apparatus using the imprint technique adopts a die-by-die alignment method as an alignment method between the substrate and the mold. In the die-by-die alignment method, for each imprint region where an imprint process is performed on the substrate, a substrate-side mark and a mold-side mark are optically detected to correct a deviation in the positional relationship between the mold and the substrate.
Japanese Patent Laid-Open No. 2012-084732 discloses a method of driving, based on the detection results of a substrate-side mark and a mold-side mark, a substrate stage so as to adjust the relative positions of a mold and an imprint region of the substrate after the mold and a resin on the substrate contact each other.
Unlike the pattern formation technique of a conventional projection optical system, the imprint technique performs die-by-die alignment such that the resin on the substrate and the mold contact each other when forming the patterns, and the relative positions of the substrate and the mold become small by driving the substrate stage. Since the resin on the substrate and the mold contact each other, the mold can be dragged by the driving of the substrate stage during die-by-die alignment and may deviate from its position with respect to an imprint head (mold holding unit). As the position deviation of the mold increases, the driving amount of alignment between the substrate and the mold during die-by-die alignment of a next shot becomes large. Furthermore, since the substrate and the mold contact each other, an amount by which the substrate and the mold can be aligned during die-by-die alignment is limited, and it takes much time for alignment.
Therefore, the position deviation between the substrate and the mold increases by repeating the imprint processes of forming the patterns on the substrate. As a result, alignment cannot be performed during die-by-die alignment or it takes much time even if alignment can be performed. Further, the mold-side mark or the substrate-side mark falls outside the field of view of an alignment scope as the position deviation between the substrate and the mold increases. As a result, the relative positions of the mold and the imprint regions may not be measured.